(At around one hour and twelve minutes) The photograph raised up the wall to replace the one shot by Andrew is of Dame Agatha Christie.
The reason this film is so difficult to find on streaming is because it fell into the hands of a pharmaceutical company called Bristol-Myers Squibb, who dissolved their entertainment division shortly after creating it, leaving this movie's distribution rights in limbo. It has since never been re-acquired or restored as of early 2022.
Sir Michael Caine was so very much beside himself to be working with Lord Laurence Olivier that he didn't even know how to address him. Eventually, he broke down and just asked. Olivier replied "Well, I am the Lord Olivier and you are Mr. Michael Caine. Of course, that's only for the first time you address me. After that I am Larry, and you are Mike."
In Andrew Wyke's cellar, a life preserver from the R.M.S. Mauretania is seen hanging from a wooden post. Built in 1906, the R.M.S. Mauretania was a luxury ocean liner owned by the Cunard line. She was a sister ship of the R.M.S. Lusitania. For 30 years, the Mauretania carried upper-class passengers between Liverpool and New York City. When she was scrapped in 1935, the Mauretania's first class reading-writing room was moved to Pinewood Studios in London (where the cellar scenes were filmed), and became the studio's board room.